In a vehicle such as a motorcycle equipped with an antilock control device, an inertia type wheel deceleration sensor is operatively connected to a wheel.
The inertia type wheel deceleration sensor is adapted to sensitively detect a variation in deceleration of a wheel by utilizing a rotation inertia force of a flywheel. Thus, it is necessary to rotate the flywheel at a speed higher than that of the wheel. In view of this fact, in a conventional braking system of the aforesaid kind, the wheel is jointed to a driving shaft for the sensor via an exclusively-used overdrive device (refer to, for instance, Japanese Patent Laid Open No. 120440/1981).
However, it has been found that when the braking system having the aforementioned type of overdrive device is applied to for example a rear wheel braking system for a motorcycle as it is, the overdrive device must be especially jointed to the rear wheel in addition to a transmission for driving the rear wheel. Thus, there arises a problem that a structure around the rear wheel becomes complicated.